Portable coolers or ice chests for keeping foods and beverages cold, are usually of a weight and size for being conveniently carried and transported by a user. Such coolers are thermally insulated to retain the cooling effect of ice or other pre-frozen cooling materials placed in the cooler chamber along with the foods or beverages. Inexpensive coolers are commonly made from materials such as expanded or foamed cellular polystyrene while more expensive containers incorporate rigid plastic container walls. Although ice is often readily available, replenishment of the ice or the cooling material may be quite inconvenient at a camping, picnic or recreational site. For larger coolers, sufficient quantities of ice may not be available for initially packing the cooling chamber. The presence of water in the cooler chamber from the melting ice is also often undesirable unless food containers and wrappers are waterproof and adequately sealed. Other portable coolers incorporate conventional refrigeration systems using freon or CFC's and small electrically powered compressors requiring 12-volt DC or 120 volt AC power sources, or Peltier effect systems. Once unplugged from the power source, these coolers no longer operate. In addition to portable coolers intended for recreational use, there exists a need for portable coolers capable of storing special goods, for example, medical products or other valuable or highly perishable materials within specific and critical temperature ranges for relatively long time periods advantageous when such goods are to be stored or shipped and where conventional refrigeration equipment is not available or is impractical.
The portable cooler of the present invention offers an alternative to using ice or other pre-frozen cooling materials, thereby obviating the disadvantages and inconvenience of using and replenishing ice common with the above-described coolers. Moreover, coolers of the invention do not require a source of electrical power for cooling operation. In another embodiment, a two reactor assembly apparatus is provided in which the evaporator is replaced by a reactor assembly. A different complex compound is used in each of the two reactor assemblies. Although such a power source is used to charge the system, once charged, the cooler will typically operate for hours without need of electrical power. In yet another embodiment, the evaporator and reactor, or two reactors, may be reversed to provide a heat storage container.